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Particle Size and Structural Effects in Platinum Electrocatalysis
JOURNAL OF APPLIED ELECTROCHEMISTRY 20 (1990) 537-548 REVIEWS OF APPLIED ELECTROCHEMISTRY 23 Particle size and structural effects in platinum electrocatalysis S. MUKERJEE Tata Energy Research Institute, 7 Jor Bagh, New Delhi-llO 003, India Received 4 January 1989; revised 18 October 1989 Of the several factors which influence electrocatalytic activity, particle size and structural effects are of crucial importance, but their effects and mechanism of interaction, vis-a-vis overall performance, have been, at best, vaguely understood. The situation is further aggravated by the use of a wide range of experimental conditions resulting in non-comparable data. This paper attempts systematically to present the developments to date in the understanding of these structural interactions and to point out areas for future investigation. The entire content of this review has been examined from the context of the highly dispersed Pt electrocatalyst, primarily because it has been examined in the greatest detail. In the first two sections a general idea on the correlations between surface microstructure and geometric model is presented. Subsequently, indicators of a direct correlation between particle size and catalyst support synergism are considered. The structural and particle size effect on electro- catalysis is examined from the point of view of anodic hydrogen oxidation and cathodic oxygen reduction reactions. The hydrogen and oxygen chemisorption effects, presented with the discussion on the anodic and cathodic electrocatalytic reactions, provide important clues toward resolving some of the controversial findings, especially on the dependence of particle size on the anodic hydrogen oxidation reaction. Finally, the effect of alloy formation on the cathodic oxygen reduction reaction is discussed, providing insights into the structural aspect. -
Monolithic Substrate Support Catalyst Design Considerations for Steam Methane Reforming Operation
Rev Chem Eng 2017; aop Luqmanulhakim Baharudin and Matthew James Watson* Monolithic substrate support catalyst design considerations for steam methane reforming operation DOI 10.1515/revce-2016-0048 as compared to other processes discussed by Baharudin Received October 16, 2016; accepted March 10, 2017 and Watson (2017). In this review paper, a monolithic structured packing for steam methane reforming (SMR) Abstract: This paper reviews the research undertaken to reactor will be studied. This novel reactor packing offers study the design criteria that address the monolithic sup- the benefits of overcoming the heat conduction limitation port structure requirements in steam reforming opera- in the current industrial-scale reformers, process intensi- tion for the effective mass transfer of process gases to the fication for an overall plant optimization, and materializ- active sites and effective conductive heat transfer through ing the concept of compact reformer. SMR is expressed by tube wall to the active catalytic areas, as well as low pres- (Saito et al. 2015). sure drop operation. Design considerations include selec- tion of substrate materials that possess good mechanical CH42+↔HO CO + 3 H2 (1) strength to withstand the severe reaction conditions and prevent catalyst crushing that would lead to carbon for- In a nutshell, a monolithic structure is a single structure mation and catalyst deactivation, and excessive heating consisting of thin-walled narrow channels that are paral- of the tube that results in hot spots which is fatal to tube lel to each other (Heck et al. 2001, Roy et al. 2004, Zamani- lifetime. The support’s mechanical properties are listed yan et al. -
SILICA CATALYSTS High Performance Polyolefin Catalysts & Supports High Performance Polyolefin Catalysts & Supports
SILICA CATALYSTS High Performance Polyolefin Catalysts & Supports High Performance Polyolefin Catalysts & Supports World class PQ is a key global supplier of chrome-on-silica catalysts and modified chrome catalysts, widely used catalysts & supports in the polymerization of ethylene into polyethylene. designed to With a manufacturing history stretching back over give exceptional 200 years, PQ prides itself on being a manufacturer performance within that offers customers; the polyolefin • Consistent product quality market • Reliable product supply • Customised solutions • Expert technical service PQ silica supports are used in the production of • HDPE chrome, Ziegler-Natta and single site catalysts that are subsequently used to manufacture polyethylene, • LLDPE polypropylene and other polymers. These polymers • PP are used in a wide variety of applications including films and sheets, pipes and tubes, blow-moulded containers and automobile parts, and wire and • Gas Phase cable sheathings. • Slurry Phase PQ supports are used in both gas-phase and slurry- phase processes. High Performance Polyolefin Catalysts & Supports THE BENEFITS OF PQ PRODUCTS High Purity As a result of the strict control of raw materials and advanced process technologies, PQ produces silica supports that have low levels of impurities. PQ is the world leader in the production of sodium silicate, a key raw material in the production of silica supports, so the quality of this critical feedstock is directly managed. Uniform Products Through the careful control of critical process steps, PQ produces products that are highly uniform at both a macroscopic level (batch to batch consistency) and a microscopic level (particle to particle uniformity). Customizable Catalysts In addition to chrome-on-silica PQ also offers modified chromium catalysts containing aluminium, titanium and other elements to provide performance enhancements needed for certain end uses, such as reduced induction time and increased activity, melt flow index and ESCR. -
Heterogeneous Catalysis Using Supported Metal Nanoparticles for Environmental Applications
Heterogeneous catalysis using supported metal nanoparticles for environmental applications Thesis submitted in accordance with the regulations of the University of Cardiff for the degree of Doctor of Philosophy By Khaled Fadhi F. Alshammari School of Chemistry Cardiff University 2018 Declaration This work has not been submitted in substance for any other degree or award at ths or any other university or place of learning, nor is being submitted concurrently in candidature for any degree or other award. Signed………………………………………… (candidate) Date …………………..... Statement 1 This thesis is being submitted in partial fulfilment of the requirements for the degree of ……PhD……….. (insert MCh, MD, MPhil, PhD, etc, as appropriate). Signed………………………………………… (candidate) Date …………………..... Statement 2 This thesis is the result of my own independent work/investigation, except where otherwise stated, and the thesis has not been edited by a third party beyond what is permitted by Cardiff University’s Policy on the Use of Third-Party Editors by Research Degree Students. Other sources are acknowledged by explicit references. The views expressed are my own. Signed………………………………………… (candidate) Date …………………..... Statement 3 I hereby give consent for my thesis, if accepted, to be available online in the University’s Open Access repository and for inter-library loan, and for the title and summary to be made available to outside organisations. Signed………………………………………… (candidate) Date …………………..... Statement 4: Previously Approved Bar on Access. I hereby give consent for my thesis, if accepted, to be available online in the University’s Open Access repository and for inter-library loans after expiry of a bar on access previously approved by the Academic Standards and Quality Committee. -
Graphene As Catalyst Support: the Influences of Carbon Additives and Catalyst Preparation Methods on the Performance of PEM Fuel Cells
CARBON 58 (2013) 139– 150 Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/carbon Graphene as catalyst support: The influences of carbon additives and catalyst preparation methods on the performance of PEM fuel cells Angela Marinkas a, Francesco Arena a, Jens Mitzel a,Gu¨ nther M. Prinz b, Angelika Heinzel c, Volker Peinecke c, Harald Natter a,* a Saarland University, Physical Chemistry, Campus Geb. B2 2, D-66123 Saarbru¨ cken, Germany b University Duisburg-Essen, Experimental Physics and CENIDE, Lotharstraße 1, D-47057 Duisburg, Germany c ZBT Duisburg, The Fuel Cell Research Center GmbH, Carl-Benz-Str. 201, D-47057 Duisburg, Germany ARTICLE INFO ABSTRACT Article history: The reduction of the platinum amount for efficient PEM (polymer electrolyte membrane) Received 17 November 2012 fuel cells was achieved by the use of graphene/carbon composites as catalyst support. Accepted 19 February 2013 The influences of the carbon support type and also of the catalyst preparation method Available online 27 February 2013 on the fuel cell performance were investigated with electrochemical, spectroscopic and microscopic techniques. Using pure graphene supports the final catalyst layer consists of a dense and well orientated roof tile structure which causes strong mass transport limita- tions for fuels and products. Thus the catalysts efficiency and finally the fuel cell perfor- mance were reduced. The addition of different carbon additives like carbon black particles or multi-walled carbon nanotubes (MWCNT) destroys this structure and forms a porous layer which is very efficient for the mass transport. The network structure of the catalyst layer and therefore the performance depends on the amount and on the morphol- ogy of the carbon additives. -
Heterogeneous Catalytic Oligomerization of Ethylene
Heterogeneous Catalytic Oligomerization of Ethylene Oliver Dennis Jan A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Washington 2017 Reading Committee: Fernando Resende, Chair Rick Gustafson Anthony Dichiara Program Authorized to Offer Degree: School of Environmental and Forest Sciences © Copyright 2017 Oliver Dennis Jan ii University of Washington Abstract Heterogeneous Catalytic Oligomerization of Ethylene Oliver Dennis Jan Chair of the Supervisory Committee: Assistant Professor Fernando Resende School of Environmental and Forest Sciences Throughout this work, we report results for the oligomerization of ethylene over Ni-Hβ in a packed bed reactor. We performed a parameterized study over temperature (30ºC-190ºC), pressure (8.5-25.6 bar), and weighted hourly space velocity (2.0-5.5 hr-1). We observed that the ethylene conversion increased with reaction pressure due primarily to the slower velocities at higher pressures. Increasing the temperature of the reactor led to the formation of larger oligomers and coke, but its effect on the conversion was small. The space velocity played an important role on ethylene conversion and product selectivity, with higher conversions observed at lower space velocities and higher selectivities to butene at higher space velocities. We also conducted a long experiment to determine the activity of the Ni-Hβ catalyst over 72 hours-on-stream at 19.0 bar partial pressure of ethylene, 120ºC, and 3.1 hr-1 WHSV. We observed that catalyst deactivation occurred only during the startup period largely due to coke formation. Despite this initial iii deactivation, negligible coke formation occurred after 8 hours time-on-stream, as the conversion remained steady at 47% for the duration of the experiment. -
Three-Way Catalysts in Passive Selective Catalytic Reduction Systems Calvin Thomas
University of South Carolina Scholar Commons Theses and Dissertations Fall 2018 Three-Way Catalysts in Passive Selective Catalytic Reduction Systems Calvin Thomas Follow this and additional works at: https://scholarcommons.sc.edu/etd Part of the Chemical Engineering Commons Recommended Citation Thomas, C.(2018). Three-Way Catalysts in Passive Selective Catalytic Reduction Systems. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/5067 This Open Access Dissertation is brought to you by Scholar Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. THREE-WAY CATALYSTS IN PASSIVE SELECTIVE CATALYTIC REDUCTION SYSTEMS by Calvin Thomas Bachelor of Chemical Engineering Auburn University, 2013 Submitted in Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy in Chemical Engineering College of Engineering and Computing University of South Carolina 2018 Accepted by: Jochen Lauterbach, Major Professor William Mustain, Committee Member Erdem Sasmaz, Committee Member Todd Toops, Committee Member Cheryl L. Addy, Vice Provost and Dean of the Graduate School © Copyright by Calvin Thomas, 2018 All Rights Reserved. ii DEDICATION This work is dedicated to my brothers and sisters: Micah, Megan, Charles, Jessica, and Alexandra. They have been with me through my whole life and I wouldn’t be where or who I am without them. It is also dedicated to my dog Fritz because he is a very good boy. iii ACKNOWLEDGEMENTS First and foremost, I would like to thank my advisor, Professor Jochen Lauterbach for accepting me into the Strategic Approaches to the Generation of Electricity (SAGE) research group. -
Recent Advances of Titanium Dioxide (Tio2) for Green Organic Synthesis
RSC Advances View Article Online REVIEW View Journal | View Issue Recent advances of titanium dioxide (TiO2) for green organic synthesis Cite this: RSC Adv.,2016,6,108741 Lee Eng Oi,a Min-Yee Choo,a Hwei Voon Lee,a Hwai Chyuan Ong,b Sharifah Bee Abd Hamida and Joon Ching Juan*ac Titanium dioxide (TiO2) has become increasingly popular as a catalyst. Although many applications of TiO2 involve photocatalysis and photoelectrochemical reactions, there are numerous interesting discoveries of TiO2 for other reactions. This review focuses on the recent development of TiO2 as a catalyst in green organic synthesis including in hydrodeoxygenation, hydrogenation, esterification/transesterification, the water–gas shift reaction, and visible light-induced organic transformation owing to its strong metal- Received 13th September 2016 support interaction (SMSI), high chemical stability, acidity, and high redox reaction at low temperature. Accepted 29th October 2016 The relationship between the catalytic performance and different metal or metal oxide dopants, and DOI: 10.1039/c6ra22894a different polymorphs of TiO2 are discussed in detail. It is interesting to note that the reduction www.rsc.org/advances temperature and addition of promoters have a significant effect on the catalytic performance of TiO2. sized scale, can iname the lungs. An occupational daily expo- 1. Introduction 8 sure limit of 15 mg of TiO2 dust has been set by the OSHA. Titanium dioxide is known as titanium(IV) oxide or titania, with Unlike other dust, TiO2 dust does not cause scarring as it is not the chemical formula TiO2. Compared with bulk TiO2, TiO2 chemically irritating to the lungs. -
Reduced Graphene Oxide-Supported Pt-Based Catalysts for PEM Fuel Cells with Enhanced Activity and Stability
catalysts Article Reduced Graphene Oxide-Supported Pt-Based Catalysts for PEM Fuel Cells with Enhanced Activity and Stability Irina V. Pushkareva 1,2 , Artem S. Pushkarev 1,2,3 , Valery N. Kalinichenko 2,4,5, Ratibor G. Chumakov 2,3, Maksim A. Soloviev 1,2, Yanyu Liang 6, Pierre Millet 7 and Sergey A. Grigoriev 1,2,8,* 1 National Research University “Moscow Power Engineering Institute”, 14, Krasnokazarmennaya st., 111250 Moscow, Russia; [email protected] (I.V.P.); [email protected] (A.S.P.); [email protected] (M.A.S.) 2 National Research Center “Kurchatov Institute”, 1, Akademika Kurchatova sq., 123182 Moscow, Russia; [email protected] (V.N.K.); [email protected] (R.G.C.) 3 Moscow Institute of Physics and Technology, 9, Institutskiy per., Dolgoprudny, 141701 Moscow Region, Russia 4 N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russia 5 N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119991 Moscow, Russia 6 College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China; [email protected] 7 Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris-Saclay, 91405 Orsay, France; [email protected] 8 HySA Infrastructure Center of Competence, Faculty of Engineering, North-West University, Potchefstroom 2531, South Africa * Correspondence: [email protected] or [email protected] Citation: Pushkareva, I.V.; Pushkarev, A.S.; Kalinichenko, V.N.; Abstract: Platinum (Pt)-based electrocatalysts supported by reduced graphene oxide (RGO) were Chumakov, R.G.; Soloviev, M.A.; synthesized using two different methods, namely: (i) a conventional two-step polyol process using Liang, Y.; Millet, P.; Grigoriev, S.A. -
Wire-Mesh Honeycomb Catalysts for Selective Catalytic Reduction of NO with NH3
Korean J. Chem. Eng., 23(6), 888-895 (2006) SHORT COMMUNICATION Wire-mesh honeycomb catalysts for selective catalytic reduction of NO with NH3 Jie Yao*, Jin Seong Choi**, Kyung Shik Yang**, Dezhi Sun* and Jong Shik Chung*,**,† *School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, P. R. China **Department of Chemical Engineering and School of Environmental Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea (Received 7 February 2006 • accepted 3 July 2006) Abstract−Both flat and corrugated wire mesh sheets were coated with aluminum powder by using electrophoretic deposition (EPD) method. Controlled thermal sintering of coated samples yielded uniform porous aluminum layer with a thickness of 100 µm that was attached firmly on the wire meshes. Subsequent controlled calcination formed a finite thickness of Al2O3 layer on the outer surface of each deposited aluminum particles, which resulted in the formation of Al2O3/Al double-layered composite particles that were attached firmly on the wire surface to form a certain thickness of porous layer. A rectangular-shaped wire-mesh honeycomb (WMH) module with triangular-shaped channels was manufactured by packing alternately the flat sheet and corrugated sheet of the Al2O3/Al-coated wire meshes. This WMH was further coated with V2O5-MoO3-WO3 catalyst by wash-coating method to be applied for the selective cat- alytic reduction (SCR) of NO with NH3. With an optimized catalyst loading of 16 wt%, WMH catalyst module shows more than 90% NO conversion at 240 oC and almost complete NO conversion at temperatures higher than 300 oC at GHSV 5,000 h−1. -
New Catalytic Concepts from New Materials: Understanding Catalysis from a Fundamental Perspective, Past, Present, and Future
Journal of Catalysis 216 (2003) 12–22 www.elsevier.com/locate/jcat New catalytic concepts from new materials: understanding catalysis from a fundamental perspective, past, present, and future Gary L. Haller Department of Chemical Engineering, Yale University, PO Box 208286, New Haven, CT 06520-8286, USA Received 8 July 2002; revised 21 August 2002; accepted 9 September 2002 Abstract The thesis of this review is that new catalytic concepts may be derived or discovered from new materials or newly recognized material properties. This thesis is demonstrated by a brief discussion of four materials, and the associated concepts, which enjoyed a certain fashion in the Journal of Catalysis and became themes of the author’s research. The four materials (or material properties) described are restricted to platinum (exemplary in most cases) supported on TiO2, yttrium-stabilized zirconia, L–zeolite, and the mesoporous molecular sieve, MCM- 41. While it was not recognized at the time, nor was it the driving force for the author’s interest, all four materials can be shown to alter catalysis by a kind of metal–support interaction that, in part or entirely, underlies the concept that is being illustrated. Thus, the common metal Pt and the emphasized catalytic property, interaction between a metal particle and an oxide support, are used as the glue to hold together a discussion of otherwise disparate catalytic systems whose selection was dictated by the interests of the author. 2003 Elsevier Science (USA). All rights reserved. 1. Introduction or two publications got my attention, and that of many others in heterogeneous catalysis research, and we all competed to As we survey progress of advancing our understanding understand the new phenomena, to ascertain the new concept of heterogeneous catalysis, our interest will be on new the particular new catalytic material was trying to teach us. -
Titanium Dioxide As a Catalyst in Biodiesel Production
catalysts Review Titanium Dioxide as a Catalyst in Biodiesel Production Claudia Carlucci *, Leonardo Degennaro and Renzo Luisi Flow Chemistry and Microreactor Technology FLAME-Lab, Department of Pharmacy–Drug Sciences, University of Bari “A. Moro” Via E. Orabona 4, 70125 Bari, Italy; [email protected] (L.D.); [email protected] (R.L.) * Correspondence: [email protected]; Tel.: +39-080-544-2251 Received: 30 November 2018; Accepted: 20 December 2018; Published: 11 January 2019 Abstract: The discovery of alternative fuels that can replace conventional fuels has become the goal of many scientific researches. Biodiesel is produced from vegetable oils through a transesterification reaction that converts triglycerides into fatty acid methyl esters (FAME), with the use of a low molecular weight alcohol, in different reaction conditions and with different types of catalysts. Titanium dioxide has shown a high potential as heterogeneous catalyst due to high surface area, strong metal support interaction, chemical stability, and acid–base property. This review focused on TiO2 as heterogeneous catalyst and its potential applications in the continuous flow production of biodiesel. Furthermore, the use of micro reactors, able to make possible chemical transformations not feasible with traditional techniques, will enable a reduction of production costs and a greater environmental protection. Keywords: titanium dioxide; heterogeneous catalyst; biodiesel; continuous flow 1. Introduction Public attention to energy consumption and related emissions of pollutants is growing. The constant increase in the cost of raw materials derived from petroleum and the growing concerns of environmental impact have given considerable impetus to new products research from renewable raw materials and to technological proposal solutions that reduce energy consumption, use of hazardous substances and waste production, while promoting a model of sustainable development and social acceptance [1–3].